Bellows-forming apparatus

ABSTRACT

An improved roll-forming machine of the kind in which a blank is corrugated by passage between parallel roll assemblies provided with convolution-forming mandrels. In the improved machine the mandrels are respectively mounted to nested and vertically slidable sleeves. Means are provided for sensing the shortening which the blank undergoes during forming and for proportionally positioning the various sleeves to minimize vertical shifting of the mandrels relative to their respective convolutions.

United States Patent [1 Harless et a1.

[73] Assignee:

[22] Filed:

Inventors:

Appl. No.:

US. Cl..... Int. Cl

BELLOWS-FORMING APPARATUS Charles E. Harless, West Paducah, Ky.; Ward G. Taylor, Vienna, [11.

The United States of America as represented by the United States Energy Research and Development Administration, Washington, DC.

Sept. 19, 1974 72/84; 72/110; 113/116 B B2ld 15/06 Field of Search 72/84, 110; 113/116 B;

References Cited UNITED STATES PATENTS 4/1929 Zimmerman................... 2/1969 Banks 4/1969 Mclnnis 1. 113/1 16 June 3, 1975 3,564,888 2/1971 Miller 72/110 FOREIGN PATENTS 0R APPLICATIONS 759,099 10/1956 United Kingdom 72/84 Primary Examiner--Lowell A. Larson Attorney, Agent, or Firm-Dean E. Carlson; David S. Zachry; Fred 0. Lewis [57] ABSTRACT 10 Claims, 5 Drawing Figures 3 I I l I651 l 'l' wnn :0 F '1 H l 1 1 1 Jig-31 53 1 2| 1 BELLOWS-FORMING APPARATUS This invention was made in the course of, or under. a contract with the US. Atomic Energy Commission.

BACKGROUND OF THE INVENTION This invention relates generally to machines for forming corrugated articles, such as annular bellows. More particularly. it relates to improvements in corrugating machines of the kind including a pair of parallel rolls provided with spaced circumferential mandrels, the mandrels on one roll being disposed in interleaving relation with those on the other. In a typical machine of this kind. one of the rolls is rotatably driven and the other is an idler. Means are provided for driving one of the rolls toward the other. so that as an annular metal blank is fed between the rolls it is clamped between the mandrels and folded thereby into serpentine shape. The driven roll advances the blank and imparts rotation to the idler. The blank makes several revolutions through the rolls, during which period the rolls are moved closer together either incrementally or continu' ously until each mandrel has formed a convolution of the desired depth. To promote folding of the blank, downward pressure is applied to its upper edge continuously, as by a hydraulic cylinder. The various mandrels are mounted to slide freely along their respective rolls; thus, as the blank shortens axially during forming, each mandrel is carried downward by its respective convolution. Ideally, once a mandrel has begun to form a convolution in the blank, there should be no relative vertical movement, or shifting, between the mandrel and its convolution throughout the forming operation.

Rolling machines of the kind just described do not form bellows which are as uniform as is desired. That is, blanks processed in such machines often are subjected to non-uniform thinning and working, with the result that even a highly uniform blank may be formed into a bellows whose wall thickness varies to an undesirable extent. Variations in wall thickness may adversely affect the operating characteristics and service life of the bellows. Even when identical blanks are processed under identical conditions in a rolling machine of the kind described, the products may not have highly similar properties.

We have found that a significant cause of the abovementioned non-uniformities is the use of free-floating mandrels to form the convolutions. Such mandrels sometimes jump out of their convolutions during the initial phase ofthe forming operation (when the convolutions are shallow), thus distorting the blank. Even when remaining in a convolution, floating mandrels sometimes shift vertically relative to the blank, causing undesirable working or thinning of the metal.

SUMMARY OF THE INVENTION It is, therefore. an object of this invention to provide a novel machine for roll-forming blanks (such as flat, arcuate, or annular sheets) into corrugated, or convoluted. articles.

It is another object to provide novel mandrcl-and-roll assemblies for use in such machines.

It is another object to provide a roll-forming machine for the rotatablemandrel type. said machine including means for sensing the shortening of a blank being formed therein and for positively positioning the various mandrels as required to accommodate such shortcning.

It is another object to provide a forming machine having rolls provided with convolution-forming mandrels whose vertical position on the rolls are controlled positively throughout a forming operation.

Other objects will be made evident hereinafter.

This invention can be characterized broadly as follows: An apparatus including a pair of parallel and axially extending rotatable assemblies for cooperatively forming convolutions in a blank positioned therebetween and thus effecting progressive shortening of said blank in a direction transverse to said convolutions. each of said assemblies including a rotatable shaft carrying a plurality of axially movable, circular mandrels, the mandrels of one assembly in interleaving relation with those of the other assembly, the improvement comprising first and second pluralities of axially slidable sleeves respectively mounted to the shafts of said assemblies, said sleeves circumferentially supporting individual ones of said mandrels, each of said sleeves coaxial with its respective mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of various components of an improved bellows-forming machine designed in accordance with this invention,

FIG. 2 is a side view of the improved machine as positioned to form an annular blank into a bellows. Clamping rings for the top and bottom edges of the blank are shown in cross section,

FIG. 3 is a side view of the arrangement shown in FIG. 2 as positioned at the end ofa bellows-forming operation,

FIG. 4 is a perspective view ofa typical mandrel-androll assembly employed in the improved machine shown in FIGS. 1-3, and

FIG. 5 is a section view taken along lines 5-5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT This invention is broadly applicable to machines having a pair of rolls provided with axially movable circumferential mandrels, the mandrels on one roll being adapted to cooperate with the mandrels on the other roll to engage a blank and fold-the same into corrugated form. For brevity, the invention will be illustrated in terms of an improved machine for forming an annu lar metal blank into an axially expandable bellows having three exterior U-shaped convolutions of the same size.

Referring to FIGS. 1-3, the improved machine includes a pair of vertical and generally similar rolls 1 and 3, each provided with circumferential mandrels M (to be described). The rolls 1 and 3 are disposed alongside the outside and inside, respectively, of an annular hori zontally disposed track 5. The track is rotatable, being supported by rollers or the like (not shown). Removably attached to the inner edge of the track 5 is a band 7 for clamping the lower edge of an upstanding annular metal blank 9 to the inside of the track.

As shown in FIGS. 1-3, a ring ll rests on the upper edge of the blank 9 and is secured thereto by a removable clamping band l3 (FIGS. 2 and 3). The top surface of the ring 11 is horizontal and is provided with an annular groove 15. This groove is in register with the blank and serves as a track for a wheel 17. The wheel 17 is part of a linkage to be described.

Roll 1 is rotatably driven by any suitable means (not shown). such as a conventional gear train powered by an electric motor. Roll 3 is movable toward and away from roll 1. being mounted on a platform 19 (FIG. 1) which is pivoted at one end and whose other end is coupled to a conventional screw drive (not shown) or to any other suitable means of reciprocation. Referring to FIGS. 2-4, the rolls l, 3 are of generally similar construction, each including a flanged cylindrical hub 21, or shaft, which is rotatably supported by a pedestal 23 (FIG. 4). As mentioned, the lower end of the hub for the drive roll 1 is coupled to any suitable means for rotation. As shown, each of the hubs carries three nested and vertically slidable sleeves 25, 27, and 29. The three nested sleeves are of different lengths, the inside sleeve 25 being the longest, and the outside sleeve 29 being the shortest. The inside sleeve 25 is slidably fitted on the upper end of the hub 21.

Each of the above-mentioned sleeves is formed near its lower end with an external flange 30 (FIG. 3) for rigid attachment of an assembly consisting of an annular spacer 31 mounted on an annular mandrel M. The mandrels extend beyond the spacers by a distance somewhat greater than the depth of the convolutions to be formed. Each mandrel has a thickness corresponding to the inside width of the typical convolution, and each spacer has a thickness approximating the outside width of the same.

As shown in FIG. 4, the upper end portions of the sleeves 25, 27, and 29 are formed with pairs of interiorly extending guide blocks 35, 37, and 39, respectively. These have mating vertical faces permitting vertical movement of the sleeves but opposing twisting or relative rotation of the same. Thus, as shown, each guide block 37 for the middle sleeve 27 has vertical faces in slidable contact with similar faces of blocks 35 and 39 for the other two sleeves.

As shown in FIGS. 2-4, a vertically extending support post 41 is rigidly mounted on the top of each hub 21. Each support post 41 terminates in a horizontal arm 43 carrying a sleeve-type bearing 45. Mounted in each bearing 45 is a vertically slidable rod 47, which is mounted coaxial with its respective roll. The lower end of each rod 47 is rigidly attached to an end of a horizontal arm 49. Two parallel links 51 (FIG. 4) are pivotally connected to arm 49', they also are connected, by means of a pivot pin S, to a pair of parallel yokesupporting arms 53. As shown, the latter are pivotally connected by means of a pivot pin P, to the aforementioned support post 41. Pivotally suspended from the support arms 53 are three yokes 55, 57, and 59, which are pivotally connected to the guide blocks for sleeves 25, 27, and 29, respectively. As shown, the yokes are provided for vertical positioning of their respective sleeves. The yokes 55, 57, and 59 are connected to the yokesupporting arms 53 at progressively greater distances from the pivot point P; thus, a given pivotal movement of the arms 53 moves the outside sleeve farther than the intermediate sleeve, and the intermediate sleeve farther than the inside sleeve.

As shown in FIGS. 2 and 3, a horizontally disposed open-ended, channel 63 normally spans the track 5. The channel is formed with slotted end portions. As indicated in FIG. 5, a sleeve-type bearing 65 is slidably mounted in either end of the channel; guides 64 permit the bearings to move horizontally but not vertically. The upper ends of the aforementioned vertical rods 47 are fitted in the slidable bushings, flanged eye bolts 67 being threaded through the guides and into the ends of the rods. This arrangement permits the roll assemblies to be moved toward and away from each other without disturbing mechanical linkage between these assem blies and the wheel 17.

As shown in FIGS. 2 and 3, a bifurcated arm 69 is pivotally suspended from the central part of the channel 63. The aforementioned wheel 17 is rotatably mounted to the lower end of this arm and rolls in the aforementioned groove 15 in the ring clamping the upper edge of the blank 9. As indicated in FIG. 2 by an arrow, during a forming operation downward pressure is applied to the wheel-carrying arm and thus to the blank 9. This downward pressure may be supplied by any suitable means, as by a centrally pivoted lever (not shown) having an end coupled to the arm 69 and its other end coupled to a conventional hydraulic cylinder. With such a pressure applied, a given downward movement (shortening) of the blank will, by means of the above-described linkage, effect the same amount of downward movement of the outer ends of the yokesupporting arms 53. As a result, the various sleeve assemblies of rolls 1 and 3 will be moved downward by preselected amounts, depending on where their respective yokes are connected to the support arms 53. In accordance with this invention, the connection points are selected so that each mandrel is moved downward at substantially the same rate as its respective convolution moves downward. The design of a specific linkage of this kind will be illustrated below.

FIGS. 2 and 3 illustrate a particular embodiment of the invention as designed for forming a specific blank into a three-convolution bellows. The blank is composed of 1/16 inch Monel and is in the form of a fully annealed ring l8 inches high and approximately I08 inches in inside diameter. FIGS. 2 and 3 illustrate the forming machine and blank as arranged at the beginning and end, respectively, of a forming operation. For this particular application, a downward application of 3,000 psi is exerted on the wheel 17 throughout the entire forming cycle. Initially, the yoke-supporting arms 53 are at an angle of 30 above the horizontal. The effective length of each yoke is preselected so that the mandrels on each roll have the desired initial vertical spacing. The roll assembly 3 is driven toward the track 5 for a sufficient distance for the mandrels to form halfinch indentations in the blank. The drive for rotating the hub 21 for roll I now is energized. The torque applied to the hub is transmitted to the mandrels of roll 1 via the support post 41 and the connections to the various sleeves. The roll 1 assembly (including the rod 47) rotates, advancing the blank-track-and-ring assembly and rotating the other roll assembly 3. At the end of one revolution, the drive for roll I is de-energized momentarily, and the roll assembly 3 again is advanced to indent the blank another half-inch. The drive for roll I is re-energized, and the sequence is repeated until convolutions of the desired depth are obtained.

FIG. 3 illustrates the apparatus at the end of the typical bellows-forming run described above. As shown. in the course of the forming operation the abovedescribed linkage moves the sleeve-and-mandrel assemblies downward as the blank shortens. At the end of the operation. the yoke-supporting arms 53 are at an angle of 30 below the horizontal. and adjacent mandrels are separated by approximately the wall thickness of the blank Access to the formed blank is provided by de-energizing the means applying pressure to the wheel [7 and by energizing the drive for roll 3 to retract the same to a position where its post-and-bcaring assembly 47. 65 (FIG. 5) separates from the channel 63. The wheel 17 and its linkage now can be lifted to expose the bellows. If desired. the bellows so formed can be stressrelieved or otherwise modified.

Given to the number of convolutions to be formed in the bellows blank, the initial spacing for the mandrels on a given roll can be calculated by techniques well known in the art. The ratios of the downward movements required for the mandrels on a given roll throughout a forming operation can be similarly calculated. In the particular bellows-forming machine shown in the figures and used to form the bellows just described, the initial center-to-center spacing ofthe mandrels is as follows:

In the embodiment shown. the spacing between pivot points P and S on the arms 53 is nine inches. As mentioned, the linkage between the top edge of the blank 9 and the arms 53 is designed so that a given downward movement of the top edge of the blank produces a like downward movement of the pivot point S. During the movement of arms 53 from the start" position (point S at 30 above the horizontal. as in FIG. 2) to finish position (point S at 30 below the horizontal. as in FIG. 3), the linkage moves each sleeve-and-mandrel assembly downward by an amount equal to the distance between pivot point P and the connection point on arm 53 for the yoke supporting that assembly. These dis tances are tabulated below.

Total Travel and Yoke No, Distance from Point P 55, inside sleeve, Roll 1 3" 57. middle sleeve. Roll l (1" 59. outside sleeve. Roll l 9" 55. inside sleeve, Roll 3 1,5" 57, middle sleeve. Roll 3 4 5" 59, outside sleeve. Roll 3 7,5"

Yoke No. Downward Movement 55. inside sleeve. Roll I 0.33" 57, middle sleeve. Roll l 06o" 59. outside sleeve. Roll 1 L00" Continued Yoke No. Downward Movement 55. inside sleeve. Roll 3 t|.l7" 57. middle sleeve. Roll 3 0.50 59, outside sleeve. Roll 3 0.83"

In tests. a bellows-forming operation of the kind described above required approximately fifteen minutes. Throughout the runs there was no evidence of vertical shifting of the various mandrels relative to the portions of the blank with which they were in contact. The wall thickness of the typical formed bellows was found to be highly uniform. varying by less than 0.005 inch.

It will be understood that the arrangement shown in the figures is for illustration only and that. given the principle of this invention, one versed in the art can make various modifications in that embodiment. For example: the inside sleeve of either roll assembly can, if desired. be keyed to its hub. Each of the posts 41 can be positioned to bear against one of the aforementioned guide blocks 35 to impart torque thereto. If desired. each of the yokes can be driven by a separate pivot arm. In the arrangement shown. the assembly 17, 69 for applying pressure to the blank is part of the linkage system; if desired, however. the means for applying pressure and the means for sensing shortening of the blank can be entirely separate. Any suitable means, such as linear variable differential transformer or other electrical displacement transducer, can be used to sense shortening of the blank, and its output can be fed to conventional (e.g., electrically powered) positioners coupled to the various sleeves. The transformer can be mounted in any suitable manner permitting its displaceable element to track, or follow, the upper portion of the blank. For example, the displaceable element can bear slidably on top or underside of the ring 13. If no such ring is employed, the element can bear directly on the top edge of the blank or on any suitable means (e.g., an annular shoulder) carried by the upper portion of the blank.

What is claimed is:

1. An apparatus including a pair of parallel and axially extending rotatable assemblies for cooperatively forming convolutions in a blank positioned therebetween and thus effecting progressive shortening of said blank in a direction transverse to said convolutions, each of said assemblies including a rotatable shaft carrying a plurality of axially movable, circular mandrels, the mandrels of one assembly in interleaving relation with those of the other assembly, the improvement comprising first and second pluralities of axially slidable sleeves respectively mounted to the shafts of said assemblies, said sleeves circumferentially supporting individual ones of said mandrels, each of said sleeves coaxial with its respective mandrel.

2. The apparatus of claim 1 wherein the sleeves of ei ther of said pluralities are in nested relation.

3. The apparatus of claim 2 wherein the sleeves of either of said pluralities are of different length.

4. The apparatus of claim 3 including means for sensing said shortening of said blank and responding to said shortening by proportionally moving said sleeves axially of their respective shafts.

5. The apparatus of claim 4 wherein said means includes an element for tracking an edge portion of said blank to sense shortening of said blank.

6. The apparatus of claim 4 wherein the nested sleeves of one of said assemblies are individually coupled to a first pivoted arm at spaced-apart points along the length of said arm. and the nested sleeves of the other of said assemblies are similarly coupled to a second pivoted arm at spaced-apart points along the length of said second arm.

7. A machine for roll-forming a blank comprising:

at first and second parallel and axially extending assemblies each including a shaft carrying a plurality of nested and axially slidable sleeves, each of said sleeves having an outwardly extending. circular mandrel coartial therewith, the mandrels of one of said assemblies in interleaving relation with those of the other of said assemblies;

b. means for moving one of said assemblies toward the other to intrude said mandrels into a blank positioned between said assemblies, thereby folding a portion of said blank and shortening said blank;

c. means for rotating at least one of said assemblies;

and

d. means for sensing said shortening of said blanks and responding to said shortening by moving said sleeves axially of their respective shafts at preselected. different rates.

8. The machine of claim 7 wherein the nested sleeves oi said first assembly are individually coupled to a first pivoted arm at spaced-apart points along its length and wherein the nested sleeves of said second assembly are individually coupled to a second pivoted arm at spacedapart points along its length.

9. The machine of claim 8 wherein said first and second arms are connected to a member which tracks an edge portion of said blank.

10. The machine of claim 9 wherein said member applies pressure to an edge of said blank to promote folding of said blank and wherein said first and second arms are mechanically linked to said element. 

1. An apparatus including a pair of parallel and axially extending rotatable assemblies for cooperatively forming convolutions in a blank positioned therebetween and thus effecting progressive shortening of said blank in a direction transverse to said convolutions, each of said assemblies including a rotataBle shaft carrying a plurality of axially movable, circular mandrels, the mandrels of one assembly in interleaving relation with those of the other assembly, the improvement comprising first and second pluralities of axially slidable sleeves respectively mounted to the shafts of said assemblies, said sleeves circumferentially supporting individual ones of said mandrels, each of said sleeves coaxial with its respective mandrel.
 1. An apparatus including a pair of parallel and axially extending rotatable assemblies for cooperatively forming convolutions in a blank positioned therebetween and thus effecting progressive shortening of said blank in a direction transverse to said convolutions, each of said assemblies including a rotataBle shaft carrying a plurality of axially movable, circular mandrels, the mandrels of one assembly in interleaving relation with those of the other assembly, the improvement comprising first and second pluralities of axially slidable sleeves respectively mounted to the shafts of said assemblies, said sleeves circumferentially supporting individual ones of said mandrels, each of said sleeves coaxial with its respective mandrel.
 2. The apparatus of claim 1 wherein the sleeves of either of said pluralities are in nested relation.
 3. The apparatus of claim 2 wherein the sleeves of either of said pluralities are of different length.
 4. The apparatus of claim 3 including means for sensing said shortening of said blank and responding to said shortening by proportionally moving said sleeves axially of their respective shafts.
 5. The apparatus of claim 4 wherein said means includes an element for tracking an edge portion of said blank to sense shortening of said blank.
 6. The apparatus of claim 4 wherein the nested sleeves of one of said assemblies are individually coupled to a first pivoted arm at spaced-apart points along the length of said arm, and the nested sleeves of the other of said assemblies are similarly coupled to a second pivoted arm at spaced-apart points along the length of said second arm.
 7. A machine for roll-forming a blank comprising: a. first and second parallel and axially extending assemblies each including a shaft carrying a plurality of nested and axially slidable sleeves, each of said sleeves having an outwardly extending, circular mandrel coaxial therewith, the mandrels of one of said assemblies in interleaving relation with those of the other of said assemblies; b. means for moving one of said assemblies toward the other to intrude said mandrels into a blank positioned between said assemblies, thereby folding a portion of said blank and shortening said blank; c. means for rotating at least one of said assemblies; and d. means for sensing said shortening of said blanks and responding to said shortening by moving said sleeves axially of their respective shafts at preselected, different rates.
 8. The machine of claim 7 wherein the nested sleeves of said first assembly are individually coupled to a first pivoted arm at spaced-apart points along its length and wherein the nested sleeves of said second assembly are individually coupled to a second pivoted arm at spaced-apart points along its length.
 9. The machine of claim 8 wherein said first and second arms are connected to a member which tracks an edge portion of said blank. 